The invention belongs to the technical field of small animal anesthesia and relates to a simple economical small animal inhalation anesthesia machine which comprises a gas steel bottle, a gas adjusting valve, a three-way pipe I, a gas flow meter I, a gas flow meter II, an isoflurane gas volatilization bottle, a three-way pipe II, an adjustable three-way pipe, an anaesthetic mask, an animal body constant temperature system, an anesthesia induction box and a gas recycling bottle. The gas steel bottle is connected with the gas adjusting valve, the three-way pipe I, the gas flow meter I, the gas flow meter II, the isoflurane gas volatilization bottle, the three-way pipe II, the adjustable three-way pipe, the anaesthetic mask, the animal body constant temperature system, the anesthesia induction box and the gas recycling bottle in sequence. Using results show that the simple economical small animal inhalation anesthesia machine is simple and reasonable in structure, various parts are fixed and combined in a coordinating mode, small animals can be subjected to anesthesia control in short time or long time, accurate anesthesia depth is guaranteed, safety is good, after operation, the morbidity and the mortality of the small animals are low, and the operation success rate is high.